Department of Microbiology & Immunology
University of Illinois
How proteins "thread" back and forth across membranes is a key question in understanding structure and, therefore, function. When a single positively charged amino acid in the sequence is removed or added, the two ends of leader-peptidase switch from the outside surface of the cell membrane to the inside surface, thus flipping the protein entirely. Fusing alkaline phosphatase into short hydrophilic regions of the maltose transport protein allows mapping of which segments were on the inside and which on the outside.
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